Anthony is at the dinner table, disgusted by the stingy portions. He throws Cleopatra an accusatory look. Where is the most expensive meal in history she promised him in a moment of careless rapture? So far, it's nothing but mussels. Just you wait, comes her answering look.

It is the picture of a climax. Cleopatra raises a hand to her earring as a servant holds out two glasses on a tray. Everyone guesses what's next. The lovers are about to consume this pearl beyond price in a single mouthful, crushed and dissolved in vinegar. And around them, mirroring the viewer's own reactions, a ring of children stretch their eyes in laughing disbelief.

Jan de Bray painted the scene in 1652 and put himself in it. He is the one with the knowing look. But this is a fairly conventional gambit compared to casting six of your siblings as extras and your elderly parents as Anthony and Cleopatra, world-class fornicators, dressed in the clothes of golden age Haarlem. Anthony, moreover, is none other than the well-known painter Salomon de Bray. And in a few years, two of the children will be painters too.

There are other painting families in art - the Bellinis, Holbeins and Cranachs, Gwen and Augustus John - but none quite so large as the de Brays: Salomon, Jan, Joseph and Dirck, Dutch contemporaries of Rembrandt. The popular belief that a gift for art must be genetic has some support in their case, for although they weren't all astounding stars - Joseph's hymn to pickled herring is as dead as the fish - they do suggest nature over nurture.

So that is one fascination of this show, seeing certain de Bray traits passed down the line. Their figures, for instance, are stocky and strong, feet on the ground and possessing real physical force. They are great at blocking a scene, too, distributing the figures left, right and centre for maximum impact. And they surely share a sense of humour: the hairy caterpillar that throws the entire focus of an exquisite still life, the hint of comedy in Anthony and Cleopatra.

But more interesting yet is the anxiety of influence, the way each son either wants or needs to get away from the art of the father. Erotic nudes, knock-out Bible scenes, portraits, histories - Salomon was infuriatingly versatile; even his family portraits were novel. The twin babies in the gigantic golden shell of a cot he designed for them are turned slightly towards each other so that you can see the psychological bond, as well as the similarity, between them.

Jan, trumping Salomon, paints his parents facing left in overlapping profile, one projecting slightly behind the other, their faces pale in the darkness. It is a marvellous conceit - husband and wife appearing to be two minds united in a single body, heading in the same direction - and a real advance in the history of portraiture.

Salomon and Anna: where are they heading? What do they see? The gravity of the painting carries an answer. Anna was already dead when the portrait was made and within a

few months every member of the extended de Bray family would be gone, carried off by the plague. The only survivors - the only memorialists - were Jan and Dirck.

The shock of this may easily be imagined from the Dulwich show, with its palpable sense of closeness. From gallery to gallery, each picture speaks to another. Salomon paints a dramatic crowd scene from below; Jan reprises the viewpoint with a pageant of orphans. Joseph paints lilies cascading from a ledge; on the same ledge, Dirck paints a hare's soft-furred corpse.

Salomon imagines Judith with the axed head of the rapist Holofernes lying in her lap like a monstrous whiskered cat; Jan goes for the jugular, with Judith raising a sword over Holofernes's naked neck. The picture is small yet all high-pitched drama, whereas Salomon's intimate scene is much larger. The one is packed, the other spare, revealing the power of empty space in a painting.

And this is the ultimate pleasure of this show, the way it focuses the mind on the infinitely different ways in which painters can come at the very same subject. The de Brays are a model family in this respect: they might share a gift, and some genes, but each has a distinct pictorial personality.